A ferrite plating method provides a fine quality ferrite film and is, for example, disclosed in Patent Document 1. The ferrite plating method comprises the steps of: preparing a specific solution containing at least ferrous ions; bringing a surface of a base body into contact with the specific solution to cause Fe2+ ions, or Fe2+ ions and other metal hydroxide ions, to be absorbed on the surface of the base body; and oxidizing the absorbed Fe2+ ions to obtain Fe3+ ions to cause the Fe3+ ions and metal hydroxide ions in the specific solution to undergo a ferrite crystallization reaction so that a ferrite film is formed on the surface of the base body.
The above-described ferrite plating method allows use of any kinds of base bodies, provided that the base bodies have tolerance to the solution. The ferrite plating method can produce a spinel-structured ferrite film under a relatively low temperature (the normal temperature to the boiling point of the solution or lower) because it is based on the reaction by using the solution. The ferrite plating method is superior to other ferrite film formation techniques in fewer limitations for the base body. The ferrite film formed through the ferrite plating method is superior in that the ferrite film, which is of ceramics, has flexibility and is easy to handle.
There are provided Patent Document 2 to Patent Document 6 and Non-Patent Document 1 as documents concerning the ferrite plating method. Patent Document 2 discloses a technique which homogenizes ferrite films formed and increases reaction rate in a ferrite film formation process. Patent Document 3 discloses a technique which makes a surface of a base body denatured and active by plasma processing so that ferrite films can be formed on the various base bodies. Patent Document 4 discloses a technique which relates to increasing ferrite film formation rate. Patent Document 5 discloses a technique which improves an insulation property of a ferrite film or a support body by coating the ferrite film or the support body with an insulation material. Patent Document 6 discloses a technique which relates to a ferrite thin film having high magnetic permeability over a wide frequency range. Patent Document 7 discloses a technique of forming a magnetic film (a ferrite film) by laminating strain-relaxation chemical compound layers and ferrite-constituent atom layers. Non-Patent Document 1 discloses a technique which relates to a noise-suppressor using the ferrite thin film based on the technique of Patent Document 6.
Patent Document 1: JPA S59-111929
Patent Document 2: JPA S60-140713
Patent Document 3: JPA S61-030674
Patent Document 4: JPA H02-166311
Patent Document 5: JPA 2005-298875
Patent Document 6: JPA 2005-191098
Patent Document 7: JPA H1-122929
Non-Patent Document 1: “GHz Conducted Noise Suppression Effects by Ferrite Thin Films Plated onto Polyimide Sheet”, NEC TOKIN Technical Review vol. 31, p. 92, 2004; Koichi Kondo, Tatsuya Chiba, Hiroshi Ono, Shigeyoshi Yoshida and Masanori Abe